?46 



THK AaRIOTTLTURAL NEWS 



iSoVt.MUJ'K i, 1^19. 



INSECT NOTES. 



INSECT PESTS IN BP4TISH GUIANA. 



The report, for the year IS 18 on the oconrrence cf iosect 

 jse^Xs of E-jgar Ci\n.2 00 thf^sMVes of ?.le.^srs. Curtis, Omiphell 

 A Co., atiT Messrs. Booker B-os.,jMt;Gor iel »fe Co., by Mr. 

 H. V?. B. Mooie, Las baea rci-tivtil. Mr. ilooie's reports on 

 tis work v.'iib iu' sot control on the.53 groups of jil.ititatious 

 Lave beeu issued anns.illy ticte I9ll, and iLiey Lave usually 

 tcsii reviefjsd in the coluuins of tLe Agrladlural JVctjs. 

 The report for 1917 was not so rtvievrtd, Lo-svevtr. l.h»; I.isS 

 previous one dealt v.ilh beicg ibat for 10 io, ibe review of 

 •which appeared ia ihe Agriciillural Nnvs, A'ol. X\'I, p. 26G, 

 August 25, 1917. 



The uotcs pi.-CoultJ Letev.ii.b av3 based piiaclpaiiy on 

 the report for 1918, bat reference will be for.nd f that of 

 1917. The insect pesis dealt \^i:.h and uiider obsetvaviou 

 ID 1 91 S were the same as io previous years, as follows: — 



The large tnotb borer (fiastnia liens), ihc sjiall mi>th 

 borers, of Trhicb tbcic arc f.vo cpecies, the blackheatled 

 {Diairaea saaharalis)^ &.i:d the yeilw-headeil {D awe'ihi), 

 the new small moth borer or the smailer sraall motU borer 

 {Elasjnopatpus Hp-oselh'^), the hardback (Dysdiieliis biden- 

 tat\xs), the weevil bcrcr {Mciamas.'us kemipkrus), wo"d!\nts, 

 locusts {Schistoceica paiunensis and .S. pallens), leaf-cai ing 

 caterpillars {Lapkygma Ji-vgiperda and Mods rcpanda), and 

 f roghopper ( Tomaspis flavi/a/era). 



The larys moth Vorer continued to be abundant on 

 certain estates, but on others the degree of infestation, wa.s 

 \^.nv. tTinr, ; , til.' p.evious year. 



The measures employed for the control of this insect are 

 the collection of the moths and caterpillars, and Hooding the 

 fields. 1. at the system of collection is r sponsible for the 

 death of many of these is indicated by the ilgures showing 

 the collections made in each of the years 1914-18. 



lable showing collections of Castnia licin : — 



Number 



These figures are not to be taken as showing relative 

 abundar-re over the whole grc".p of estates since the list does 

 not include the eame (i^fcjte.i from year to year, although 

 the number of estates does not vary much. 



In the rcpoiton the woik in 1917, Mr. Moore deals 

 at some length with thi matter of flooding. 



The pr.?.ctice of f.oC':':.'.j, Tbioh appears to be increasing 

 in extent, ii of two klinU: one called long flooding, 

 wh^n lard to bo rested is kf i",t under water for from six 



itoi tha to a y-i'- ; - " 

 flood in iiificlaiiu'! I 

 insects. ' 



It is pointed ■ 

 p!<!nt!og c.'uld b' 

 k'!l a \bt^' hirpe ^ , 



prf.ven*. to n Ip'-ge pxtnnt. the prf'wth, in the interv: 1 bt'iv 

 rcftping and 7'hn'ir.g, of cane sprouts and other vi-gcialion 

 whi' h in the ordinary way would be liable to infestation, 



r ^hort Hooding, when the 

 1 to kill Castnia and other 



Ids intended for immediate 



led, lor this would not imly 



the insects in the soil and 



, the soil, but it would also 



n 



Fields thns treated need not be ."earohed for grul.;; liiig- 

 would leave the gangs available for work in other field.s, and 

 a decided increase in vhe utili'y of the gang would thug i'e 

 brought about. 



.Mr. Moor-J attf.cka the rule of thumb method prevail- 

 in.!.' on estaie.s, vhith resulcs '.n lig'dity of pnictice when a 

 certain amount; of tlfxibilitT is necessary. It -s shown that 

 fields whiclt are n )1 Jr.e t-j bs replanted on account of s^vf le 

 infestation of irse.-t pests might be flooded, di,d the pests 

 alii ost completely killed out. 



F ' Helds i!igh5 with advantage he repls.otel nfter 

 short "ling." Long floodi-ig, which is becDiaicg mi>re and 

 more au estate piactlse, haa for its object the general 

 renovation of the so.l. Insects and other organijms are k.'.lled 

 out, the physical conoilion of ibc soil is i;npr...v.:d. ard its 

 fertility restored to a large extent. 



The smsll moth borers; wi^re still in 191.S 'he most 

 damaging of ttiR s-jgar-cane pests on th^se e>-fate8. The 

 yellow-beaded {D <uietk\) constitui;;d for itost of the lime the 

 greater bulk of the smiill moth borers. From SO to 95 ')er 

 cent, of the total v.sre of this kind during tho period frora 

 .Jauuaiy to Septei.iber. Mr. Moore reports that in au 

 unusually long and severe period of droncht the veliovv- 

 hsaded borer decreased io numbers, while the black-headed 

 (/>• sMdiari^lis) increased at th^it time. 



In 'this connexion it is stated .hat the yellow-headed ia 

 the stronger avd more vigorous form, and app.'ars to check 

 and prevent tho devel jpmont of th- weiker black bended. 



In this i-\'-tauce -'he diou«;ht appeared to luve a direct 

 etiect in reducing the number of the yellow headed, while a 

 deficiency in eg>! parasitism was responsi .le for the sjreat 

 increase of the black-headed. While the eolltctini' ot' ihe 

 egg clusters has an influence in checking the blasjk-headed 

 borer, it is of no avail agam.st the yellow-headed. At times 

 when the yellow headed is so imich in exce.ss that 90 per cent, 

 of the collected caterpillars are of this form, it has been 

 found that over 90 per cent, of the egg clusters collected 

 belonged to the black headed borer. 



' The principal way of keeping the yellow-headed in check 

 is steady, persistent, uuinteru[)ed, systetualic and reoeated 

 cutting out of the borers, the work to be begun as eoon as 

 stools start to spring, and to be continued until growth is 

 too advanced. Very helpful also would he the careful 

 selection of uninfi .^ttd t.oris for pKnting, and the immediate 

 dispoisal of unwanted tojis by deep burial, or by being 

 removed, either to bfe burnt or thrown into cro.ss-ca'ials 

 or soaked for some days in ponds containing water.' 



The flooding of fields Irom a few weeks to a year is 

 stated to be very etifective in the c.)ntrol of these borers. 

 The black-he.aded oviposits on the green cane blade, but the 

 yellow-headed does not, though the e.vact situation where 

 the eggs are laid is not yet known, and floodini; seems to 

 act as a more etlective check on the yellnw-headed than on 

 the black-headed form. 



A new small moth borer recorded in the 1917 report 

 is referred to in the report for 19 1 8 as the snvil'er small 

 moth borer. This has been indcntified as El<ismi>palpus 

 lignosellus. c 



This insect has occurred in some numbers en a few 

 estates, causing several local damage It h*s nude its 

 heaviest attacks only in dry weather, but appears to have 

 po.'<S)bilitie8 as a ,seri«U8 pest 



The small black hardback (,l\\scineln.< ln'ihiital'is) is 

 usually in evidence durini; the mid-year rainy season from 

 May to August, In 1917 the attack ot ibis pe?t was 

 very severe on ,some estates, but in 1918 was rather less. 

 Severe, o'l the whole, than in the former year. 



